1. Field of the Invention
This invention generally relates to a linear motion rolling contact guide unit, and, in particular, to such a guide unit having a high rigidity and thus suitable for use in machine tools or the like.
2. Description of the Prior Art
A linear motion rolling contact guide unit is well known in the art, and it generally includes a rail extending straight over a desired length, a slider slidably mounted on the rail and a plurality of rolling members, such as balls or rollers, interposed between the rail and the slider. A typical prior art linear motion rolling contact guide unit is described in the Japanese Pat. Laid-open Pub. No. 2-279243, and the guide unit described in this prior publication is illustrated here in FIG. 3. As shown in FIG. 3, the prior art linear motion rolling contact guide unit includes a rail 21 extending straight over a desired length and having a pair of oppositely inclined inner guide surfaces at each side thereof. The guide unit also includes a slider 20 which is slidably mounted on the rail 21 and which is also formed with a pair of oppositely included outer guide surfaces, each located opposite to a corresponding one of the pair of oppositely inclined inner guide surfaces of the rail. Thus, there are defined four guide separate channels, each defined by a pair of oppositely located inner and outer guide surfaces, between the rail 21 and the slider 20. A plurality of rollers 22, 23, 24 and 25 are provided in each of these four guide channels so that a sliding contact is provided between the rail 21 and the slider 20.
In the guide unit shown in FIG. 3, since the rolling contact between the rail 21 and the slider 20 is provided only by the rollers 22-25, the sliding resistance is extremely small so that the slider 20 may move along the rail 21 slidingly extremely smoothly. However, with this structure, the sliding resistance is too small for use in machine tools or the like and the cutting resistance cannot be shared by this guide unit. As a result, if the guide unit shown in FIG. 3 were used in machine tools, a heavy duty cutting operation could not be carried out.